In actuality it's nothing more than a simple average. There are some conditions: the equipment is beyond the initial introductory stage and not yet to the end of it's life; this middle period is sufficiently long--more than the beginning and end times combined at least. It's replaced or repaired when it fails, not scrapped or salvaged.

**Then it's the mean failure time of all such unit failures; exactly as the sum of x numbers divided by x.** It's

__not__ a statistical predictor of any sort.

To get to a prediction, one would need to know the failure rate function; obtained by knowing or estimating the failure point of all equipment of type 'N': guess the function, make a correlation/prediction. Then the mean can be used to give a statistical probability that a unit

*might *fail at any particular time. Such as 20% chance of failing in one year, or 6% chance of failing in 18 months. Such an estimate made with a small sample of units would have an accuracy directly proportional to the quality of the data-the more units known the better-up to some point.

But these don't tell which units will fail, just the number of units per 100 at any particular time. And because of the small sample quality data thing, it's mostly an exercise in statistical mumbo-jumbo as far as any individual user/owner is concerned.

While the manufacturer, Pentax in this case, might have the information to derive such a function, estimate a prediction and act, it probably wouldn't do so unless the problem item afflicted a significant number of owners. During the warrantee period there is no driving force to make such a study--just replace the unit. With the K10d we are scarcely out of the introductory period, the point where such a prediction would become meaningful. As with most manufactured commodities most of the significant problems have been found and fixed. And long before we reach the end of the cameras useful life another newer camera will probably be developed and offered at market.

Until spare parts supplies are exhausted any unit superseded by something newer is actually in a bonus period--one should, properly consider shutter activations in this period as 'gravy' or 'sauce' or a 'bonus'---the company is not going to retro-tool to make new 'old' units

*or* spare parts.

Originally posted by WMBP Yes, this is typical. John likes to be begged.

OK, I'll beg. What DOES the number mean?

Will